A local fingerprint for hydrophobicity and hydrophilicity: from methane to peptides

An important characteristic that determines the behavior of a solute in water is whether it is hydrophobic or hydrophilic. The traditional classification is based on chemical experience and heuristics. However, this does not reveal how the local environment modulates this important property. We present a local fingerprint for hydrophobicity and hydrophilicity inspired by the two body contribution to the entropy. This fingerprint is an inexpensive, quantitative and physically meaningful way of studying hydrophilicity and hydrophobicity that only requires as input the water-solute radial distribution functions. We apply our fingerprint to octanol, benzene and the 20 proteinogenic amino acids. Our measure of hydrophilicity is coherent with chemical experience and, moreover, it also shows how the character of an atom can change as its environment is changed. Lastly, we use the fingerprint as collective variable in a funnel metadynamics simulation of a host-guest system. The fingerprint serves as a desolvation collective variable that enhances transitions between the bound and unbound states

Use of Frequency Distribution Functions to Establish Safe Conditions in Relation to the Foodborne Pathogen Bacillus cereus

Minimal processing implementation greatly depends on a detailed knowledge of the effects of preservation factors and their combinations on the spoilage and foodborne pathogenic microorganisms. The effectiveness of mild preservation conditions will become increasingly dependent on a more stochastic approach linking microbial physiological factors with product preservation factors. In this study, the validity of frequency distributions to efficiently describe the inactivation and growth of Bacillus cereus in the presence of natural antimicrobials (essential oils) has been studied. For this purpose, vegetative cells were exposed to 0.6 mM of thymol or cymene, obtaining survival curves that were best described by the distribution of Weibull, since a tailing effect was observed. B. cereus was also exposed in a growth medium to a low concentration (0.1 mM) of both antimicrobials, separately or combined, and the lag times obtained were fitted to a normal distribution, which allowed a description of dispersion of the start of growth. This allowed a more efficient evaluation of the experimental data to establish safe processing conditions according to accurate parameters and their implementation in risk assessment

Differences in expression profiling and biomarkers between histological colorectal carcinomas subsets from the serrated pathway.

Histological subtypes of colorectal carcinomas (CRCs) arising from the serrated route, such as serrated adenocarcinoma (SAC) and CRC showing histological and molecular features of microsatellite instability (hmMSI-H), share common features (female gender, right-sided location, mucinous histology and altered CpG methylation) but dramatically differ in terms of prognosis, development of immune response and treatment options. Despite this, to date no expression profiling comparison has been carried out for finding out functions and molecules responsible for such differences. METHODS AND RESULTS: Molecular signatures of SAC and hmMSI-H were obtained by transcriptomic array; qPCR and immunohistochemistry (IHC) were used to validate differentially expressed genes. An over-representation of innate immunity functions (granulomonocytic recruitment, chemokine production, TLR signaling, antigen processing and presentation) were obtained from this comparison and ICAM1 was more expressed in hmMSI-H whereas two genes (CRCP and CXCL14) were more expressed in SAC. These array results were subsequently validated by qPCR, and CXCL14 and ICAM1 by IHC. Information retrieved from public databanks confirmed our findings. CONCLUSIONS: Our findings highlight specific functions and genes which provide a better understanding of the role of the immune response in the serrated pathological route and may be of help in identifying actionable molecules. This article is protected by copyright. All rights reserved.pre-print664 K

Electronic band alignment at CuGaS2 chalcopyrite interfaces

Cu-chalcopyrite semiconductors are commonly used as light absorbing materials on solar cell devices. The study of the heterointerfaces between the absorbent and the contact materials is crucial to understand their operation. In this study, band alignments of the heterojunctions between CuGaS2 chalcopyrite and different semiconductors have been theoretically obtained using density functional theory and more advanced techniques. Band alignments have been determined using the average electrostatic potential as reference level. We have found that the strain in the heterointerfaces plays an important role in the electronic properties of the semiconductors employed here. In this work CuAlSe2/CuGaS2 and CuGaS2/ZnSe heterointerfaces show band alignments where holes and electrons are selectively transferred through the respective heterojunctions to the external contacts. This condition is necessary for their application on photovoltaic devices

V-substituted In2S3: an intermediate band material with photocatalytic activity in the whole visible light range

We proposed in our previous work V-substituted In2S3 as an intermediate band (IB) material able to enhance the efficiency of photovoltaic cells by combining two photons to achieve a higher energy electron excitation, much like natural photosynthesis. Here this hyper-doped material is tested in a photocatalytic reaction using wavelength-controlled light. The results evidence its ability to use photons with wavelengths of up to 750 nm, i.e. with energy significantly lower than the bandgap (=2.0 eV) of non-substituted In2S3, driving with them the photocatalytic reaction at rates comparable to those of non-substituted In2S3 in its photoactivity range (λ ≤ 650 nm). Photoluminescence spectra evidence that the same bandgap excitation as in V-free In2S3 occurs in V-substituted In2S3 upon illumination with photons in the same sub-bandgap energy range which is effective in photocatalysis, and its linear dependence on light intensity proves that this is not due to a nonlinear optical property. This evidences for the first time that a two-photon process can be active in photocatalysis in a single-phase material. Quantum calculations using GW-type many-body perturbation theory suggest that the new band introduced in the In2S3 gap by V insertion is located closer to the conduction band than to the valence band, so that hot carriers produced by the two-photon process would be of electron type; they also show that the absorption coefficients of both transitions involving the IB are of significant and similar magnitude. The results imply that V-substituted In2S3, besides being photocatalytically active in the whole visible light range (a property which could be used for the production of solar fuels), could make possible photovoltaic cells of improved efficiency

Synthesis and characterization of transition metal-subtituted indium thiospinels as intermediate band materials for high efficiency solar cells

It was recently proposed that higher efficiency can be achieved in PV cells having a single-absorbent if for the latter an intermediate band (IB) material is used which contains a partially filled, isolated band within the gap of an otherwise normal semiconductor. In2S3 and related compounds in which octahedrally coordinated In is substituted by a light transition metal are IB material candidates according to solid state chemistry concepts, this having been confirmed by quantum calculations. Here materials of this type have been chemically synthesized in powder form using wet solvothermal methods. Especially for vanadium-substituted In2S3 , incorporation of the metal into the lattice is supported by XRD and TEM data, and only minor oxidation of vanadium from the V III state to the V IV state is evidenced by EPR. New sub-bandgap features appear in the diffuse reflectance optical spectra upon incorporation of vanadium; these coincide with the spectra that had been predicted by the quantum calculations as corresponding to the IB electronic structure. The realization of the IB concept in a single compound, that furthermore should be easy to prepare in the form needed for PV thin film cells, is thus achieved for the first time

Optical properties of novel intermediate band indium thiospinel materials by quantum mechanical calculations

In this work we present quantum mechanic calculations using the Density Functional Theory for several transition metal substituted octahedral thiospinels derivatives of the In2S3 and MgIn2S4 compounds. The calculations predict that these materials will have a partially filled band inside the band-gap of the aforementioned semiconductors and due to that can be proposed as a novel class of high efficiency photovoltaic materials for intermediate band solar cells. The new band enables absorption of additional photons with energies lower than those of the band-gap, increasing in this way the photocurrent. Results of calculations show the enhancement of the optical absorption properties. The purpose of the work is to develop a material which can be used to create a more efficient photovoltaic solar cell

Optimal sequencing and lot sizing in a multi-model synchronous assembly line

This work presents a mixed-integer nonlinear mathematical pro-gramming (MINLP) model aiming at optimizing the sum of transition and in-ventory carrying costs in a multi-model synchronous assembly line. Different products are assembled in the same line in runs or campaigns, whose sequence and length should be optimally determined. As products show different cycle times, transition periods are of particular interest due to the productivity reduc-tion. The proposed model precisely accounts for transient periods, at the time it incorporates further details such as semi-elaborate stocks. It is successfully ap-plied to a real-world case study of the argentine truck trailer industry.Sociedad Argentina de Informática e Investigación Operativa (SADIO